Computed tomography with a low-intensity proton flux: results of a Monte Carlo simulation study

Reinhard W. Schulte M.D.; Margio Cezar Loss Klock; Vladimir Bashkirov; Ivan G. Evseev; Joaquim Teixeira de Assis; Olga Yevseyeva; Ricardo Tadeu Lopes; Tianfang Li; David C. Williams; Andrew J. Wroe; Hugo Reuters Schelin

doi:10.1117/12.560031

26 October 2004 Computed tomography with a low-intensity proton flux: results of a Monte Carlo simulation study

Reinhard W. Schulte M.D., Margio Cezar Loss Klock, Vladimir Bashkirov, Ivan G. Evseev, Joaquim Teixeira de Assis, Olga Yevseyeva, Ricardo Tadeu Lopes, Tianfang Li, David C. Williams, Andrew J. Wroe, Hugo Reuters Schelin

Author Affiliations +

Proceedings Volume 5541, Penetrating Radiation Systems and Applications VI; (2004) https://doi.org/10.1117/12.560031
Event: Optical Science and Technology, the SPIE 49th Annual Meeting, 2004, Denver, Colorado, United States

Abstract

Conformal proton radiation therapy requires accurate prediction of the Bragg peak position. This problem may be solved by using protons rather than conventional x-rays to determine the relative electron density distribution via proton computed tomography (proton CT). However, proton CT has its own limitations, which need to be carefully studied before this technique can be introduced into routine clinical practice. In this work, we have used analytical relationships as well as the Monte Carlo simulation tool GEANT4 to study the principal resolution limits of proton CT. The GEANT4 simulations were validated by comparing them to predictions of the Bethe Bloch theory and Tschalar's theory of energy loss straggling, and were found to be in good agreement. The relationship between phantom thickness, initial energy, and the relative electron density uncertainty was systematically investigated to estimate the number of protons and dose needed to obtain a given density resolution. The predictions of this study were verified by simulating the performance of a hypothetical proton CT scanner when imaging a cylindrical water phantom with embedded density inhomogeneities. We show that a reasonable density resolution can be achieved with a relatively small number of protons, thus providing a possible dose advantage over x-ray CT.

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Reinhard W. Schulte M.D., Margio Cezar Loss Klock, Vladimir Bashkirov, Ivan G. Evseev, Joaquim Teixeira de Assis, Olga Yevseyeva, Ricardo Tadeu Lopes, Tianfang Li, David C. Williams, Andrew J. Wroe, and Hugo Reuters Schelin "Computed tomography with a low-intensity proton flux: results of a Monte Carlo simulation study", Proc. SPIE 5541, Penetrating Radiation Systems and Applications VI, (26 October 2004); https://doi.org/10.1117/12.560031

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